Railway car air conditioning system



March 8, 1938. H. 1.. SMITH, JR

. RAILWAY CAR AIR CONDITIONING SYSTEM Filed Aug. 17, 1935 4 Sheets-Sheet 1 BY W,WW+QZM4 ATTORNEYS March 8, 1938. H. SMITH, JR 2,110,581

RAILWAY CAR AIR CONDITiONING'SYSTEM Filed Aug. 17, less 4 Sheets-Sheet 2 INVENTOR mm a BY I f I ATTORNEYS March 1933- H. L. SMITH. JR

RAILWAY CAR AIR CONDITIONING SYSTEM Filed Aug. 17, 1935 4 Sheets-Sheet 3 lNVNTOR l k v.

ATTORNEYS March 8, 1938.

H. SMITH,VJR

RAILWAY CAR AIR CONDITIONING SYSTEM 4 Sheets-Sheet 4 INVENTOR M,

Filed Aug. 17, 1935 Patented Mar. 8, 1938 z'nusl Thermal Engin w 1:

s Con-pollution, Richmond,

We... a coration oi Virginie Application A it, 1935, Serial No. M1535 This invention relates to air conditioning and more particularly concerns an improved air conditioning system for use on railway passenger cars of steam roads.

The provision of conditioned air in railway passenger cars involves generally two conflicting problems; that of maintaining comfortable conditions and that of economy. The power available on steam trains for the operation of auxiliary equipment, such as air conditioning apparatus, is quite limited. On the other hand, passenger cars are necessarily subjected to widely varying temperature conditions'in the course of an average run and comfortable atmospheric conditions can be maintainedtherein only if a very flexible system of relatively large cooling capacity is pro all vided.

'in the past, railway car air conditioning systems have been a compromise between two desired ends, the maintenance of comfortable conditions and reasonably economical operation. Known systems operated in whole or in part by electricity involve a high initial cost and high operating expense due to their low emciency. Thus when such systems are installed on a railway car, it is necessary to replace the usual car lighting generator and battery with electrical generating and accumulating equipment 01 greatly'increased capacity and this replacement materially increases the initial cost of the installation. The energy for operating electrically driven systems is delivered from the locomotive through the draw bars, the axle driven generator, the storage battery and the electric motors to the refrigerating apparatus, and consequently, the overall eificiency of the system is low and the operating cost correspondingly high.

Steam operated railway car air conditioning systems employing steam jet vacuum boosters have been used to a certain extent, and in general, are more economical to install and operate than electrically driven systems. However, such systems operate effectively under maximum steam supply only, since the efllciency of a. steam jet or injector in creating a vacuum falls rapidly as the steam pressure on the jet is reduced, and as a practical matter, effective cooling can be obtained only if the steam is" supplied continuously at the rated pressure. The piping available for supplying steam to the various car carried units of a train is-limited in size, and when a large number of car units are in operation, the steam pressure falls off in the rearward cars and wasteful operation and insufllcient car cooling results.

In both the electrically driven and steam opereted systems now in use, the control is intermittent, the epperatus operating at maximum capacity whenever it is turnedon. Since the system must have scient capacity to prop erly cool the car under the most adverse outside 5 temperatur conditions met with in operation, the intermittent control produces undesirably wide fluctuations in car temperature under moderate outdoor conditions, and iurther results in lowered efliciency due to the power losses involved in starting the apparatus at frequent intervals.

With the above and other considerations in mind, it is proposed in accordance with the present invention to provide an improved railway our air conditioning system for steam trains which is controlled in an emcient and economical manner by varying the cooling effect in accordance with the heat load imposed whereby the our air temperature is maintained at the desiredvelue without wide fluctuations. Other objects of the invention include a system of this nature which is small and compact, inexpensive to install and low in operating cost. A further feature oi the invention involves the provision of improved and I simplified means for operating the system when the railway car is standing in a yard or station with no locomotive connected thereto whereby a car may be precooled before it is connected in a train and occupied by passengers.

In general, the above and other objects of the invention are carried out by providing a compression type reirigereting system to cool the car and driving this system with a steam prime mover capable of eflicient operation over a wide range of speeds. In accordance with the invention, the speed of the prime mover and hence the speed of the refrigerant compressor is varied by means responsive to atmospheric conditions in .the car, and in this manner, the car temperature is maintained constant at the desired value and a, very high operating emciency is obtained. I have found that a reciprocating steam engine of the uniflow type is particularly adapted for use in my improved system.

The speed control is conveniently accomplished by adjustment-of the steam supply to the prime mover and to this end, I preferably provide means responsive to both the speed of the prime mover andthe temperature of the car, whereby the compressor operates at a speed which is maintained constant in spite of steam pressure variations or variable load factors so long as the car temperature is within thedesired range, but which speed is varied to compensate for departures from the desired car temperature conditions. 5

ently of the steam engine.

Therefrigerant compressor is a constant volume device, acting on a relatively dense gas, and accordingly, the compressor efilciency increases as its speed drops. High compressor speeds result in high gas velocities and high friction losses. There is, of course, a low limit to the speed at which it is economical to operate a refrigerant compressor since the relation between the initial investment and required capacity must be taken into account. However, since heat load condi-' tions vary widely and operation is for the most part well below maximum capacity, I obtain a condsiderable increase in emciency by varying the compressor speed in accordance with load requirements since in this manner, the compressor always operates at the highest efficiency obtainable for the load imposed and further, losses resulting from frequent starts are avoided.

My improved variable speed steam driven system is better suited for use with steam supply facilities of multiple-car trains than previously known systems. With known steam systems, which are governed by a full-on or full-oi! control, the units on the several cars of a train frequently operate simultaneously and the rapid steam consumption by the forward car units so far reduces the steam pressure on the rearward car units that these units operate very inefllciently and usually fail to produce the required cooling effectuntil after the forward car units have stopped operating. With. my improved variable speed steam system, the amount of steam drawn from the train line by each unit is throttled to the minimum value which will maintain the desired car temperature under continuous operation, and sudden fluctuations of train line steam pressure with resultant ineflicient or inadequate operation of the rearward car units is avoided.

In accordance with one embodiment of my invention, I provide an. over-running clutch or equivalent means in the driving connection between the steam engine and the refrigerant compressor, and further provide an electric compressor driving motor which may be readily connected directly to drive the compressor independ- With this arrangement, the car may be pre-cooled by merely connecting the electric motor to the refrigerant compressor and supplying current from a trackside outlet, the steam engine remaining stationary during such operation because of the overrunning clutch in its driving connection.

In describing the invention in detail, reference will be made to the accompanying drawings in which;

Figure 1 is a plan view of a car carried refrigerating unit embodying the invention;

Figure 2 is a side elevation of the unit shown in Figure 1;

Figure 3 is an end elevation of the car carried unit;

Figure 4 is an enlarged detailed view, partly in section, of the compressor driving mechanism;

Figure 5 is a sectional view of the governor mechanism;

Figure 6 is a sectional elevation of a railway passenger car equipped with an air conditioning system embodying the invention; and

Figure '7 is a diagrammatic view of a trainof passenger cars equipped with systems embodying the invention.

Referring to the drawings, my improved railway car air conditioning system has been shown tional construction which has been diagrammatically illustrated at P in Figures 6 and 'l. The system is of the type in which a refrigerant from a refrigerating unit, or a suitable heat transfer medium cooled by such refrigerant, is circulated in heat exchanging relation with air supplied to or circulated in the car. The particular form of car cooling coil and air propelling means forms no part of the invention and various forms of apparatus may be employed for this purpose. In the embodiment shown in Figure 6, fresh air from outside of the car is drawn by a fan 2 through one or more intake openings 3 into a chamber 4 located above the ceiling of .the car vestibule I,

and is propelled by the fan through a duct 5 to suitably placed ceiling outlets 6 in the car. 'A cooling coil 8 is located in the chamber 4 in heat exchanging relation with the air drawn therethrnugh and this coil is at times supplied with refrigerant or other cooling fluid from a refrigerating unit hereinafter described. The fan 2 may be operated by an electric motor, as shown. The fan and motor may be of relatively small capacity and may replace the usual electric fans customarily installed in railway passenger cars. Air may be discharged from the car through the doors, windows or other air pervious openings thereof, or special air outlet ducts may be pro vided, if desired.

The refrigerant for cooling the air delivered to the car is supplied by a refrigerating unit carried beneath the car in a housing generally designated H. Thehousing may take any suitable form and is preferably disposed beneath the car frame and between the center line of the car and the clearance limits at one side thereof, as shown in Figure 3. i

The refrigerating unit proper comprises generally a mechanical refrigerant compressor 10, preferably of the reciprocating type, a refrigerant condenser C and suitable means such as the fans II and I2 for drawing a current of cooling air over the condenser surfaces. The intake I3 of the compressor III is connected to draw refrigerant gas from the car coil 8 by a pipe l4, preferably provided with ,a cut-off valve IS. The discharge IS, of the compressor I0 is connected through a pipe I! and a valve l8 to the condenser C. The outlet of the condenser C passes through a cut-off valve is and a pipe '20 to the car cooling coil 8, the proper condenser pressure being. maintained by a suitable expansion valve 2|. The condenser may take any suitable form and preferably includes finned coils or passages 22 communicating with a liquid refrigerant accumulator 23.

"Ihe condenser cooling fans H and I2 are disposed in suitable circular openings in a shield 24 extending across the inner face of the condenser C, and air drawn through the condenser passes laterally through the housing H and out through the louvers 25 in its outer wall. The fans H and I2 are journaled in suitable brackets 26 and 21 and are driven by a single shaft 28 through suitable spiral gears 29 and 30. I

The refrigerant compressor I0 is driven by a steam prime mover, which preferably comprises a direct connected reciprocating steam engine of the uniflow type, which is illustrated at E. In general, the steam prime mover employed should be capable of efllcient operation over a wide range of speeds, and I have found the uniflow type of steam engine admirably suited to this purpose. The crank shaft 3! of the engine E is connected to the compressor shaft 32 through an overrunning clutch or equivalent means 88. As shown in Figure 4, this clutch may take the form of an inner element 34 connected to the engine shaft 8| and having a plurality of cam recesses 88 therein carrying balls or rollers 88 and surrounded by an outer element 81 fixed to the compressor shaft 82. As will be understood, rotation of the inner element 84 by the engine E in a counterclockwise direction, as viewed in Figure 4, causes the rollers 38 to lock in the cam recesses 88 and so form a driving connection between the engine and the compressor. If the outer element 81 is driven independently of the engine E, the rollers 88 are released and the engine remains stationary.

I prefer to provide an electric motor for operating the compressor ll independently of the engine E when the car carrying the system is not coupled to alocomotive whereby the car maybe precooled before it is occupied by passengers. To this end, a motor 88 is provided, having a friction wheel 88 on its shaft disposed parallel to the outer member 81. of the over-running clutch. A friction idler 48 is slidably carried by a suitable bracket 4| and is movable to and from a position to simultaneously engage and form a driving connection between the motor friction wheel 39 and the outer clutch member 81. The idler 48. may be operated in any suitable manner, and as shown, a pneumatic diaphragm mechanism 42 is provided for this purpose. This mechanism includes a diaphragm 43 acting against a spring 44 and operating a plunger 45 connected to the sliding journal 48 of the idler 48. Compressed air from a suitable source is supplied to the mechanism 42 through a pipe 41 under the control of a manual three-way valve 48. when the valve 48 is manipulated to admit air pressure to the diaphragm 48, the idler is moved to engage the wheel 88 and clutch member 81, thus establishing adriving connection between the motor 88 and the compressor Hi. When the valve 48 is manipulated to cut of! the air supply and discharge air from the diaphragm chamber of the mechanism 42, the spring 44' moves the idler 48 out of engagement with the friction wheel 88 and clutch member 31, thus breaking the driving connection.

The fan operating shaft 28 is driven with the compressor l8 through a driving connection comprising the aligned'pulleys 58 and 58 and the belts 88 engaging these pulleys. The desired belt tension is maintained by an idler 5| engaging the lower span of the belts 58 and pressed against the belts by a spring 82 which is tensioned between a fixed support and the pivoted idler carrying arm 83.

Steam for operating the engine E is supplied from the locomotive 58 through the usual train steam line 5| and a branch pipe 52 leading to each car carried unit. The steam passes through a manual supply valve 53, a water separator 54, an automatic cut-off. valve 55 and a throttle valve 55 to the engine E. Exhaust steam from the t" gine E passes out of the housing H through the pipe 51.

used. The governor G disclosed is mounted on the frame of the engine E and driven from the engine shaft through suitable gearing, not shown. The governor has two centrifugally operated weighted elements 84, pivotaliy supported on a cross piece 85 fixed to the governor shaft 88. A sliding collar 81 carried by the shaft 88 is moved along this shaft by the outward movement of the centrifugal elements 84, and the movement of the collar 81 is transmitted to a shaft 88 by the arm 88. The shaft 88 carries an arm 18 outside of the governor casing, and a tensioned spring ll connected to this arm exerts a force thereon which opposes the outward movement of the centrifugal elements 84. The end of the spring 1| is connected to a pivoted lever 12, the movement of which varies the force exerted by the spring H on the lever III, as is apparent from the showing in Figure 2. A second arm 13 is connected to the shaft 58 of the governor G and is in turn connected through the links l4, l5, I8 and I1 to the stem of the steam engine throttlevalve t8. Suitable means are provided for moving the lever 12 and so varying the tension of the governor spring H in accordance with changes in air temperature within the car P. In the disclosed embodiment, this is accomplished by means of a pneumatic diaphragm mechanism 18 having a flexible diaphragm 19 connected to the lever I2 through a plunger 80. The downward movement of the diaphragm 78 and plunger 88 is opposed by a spring 8| and compressed air from a source indicated by the pipe 83 is supplied to the upper surface of the diaphragm 18 through a pipe 84 under the control of a thermostat 82 in the car. The thermostat 82' is of known construction and acts to reduce the air pressure on the diaphragm I8 as the car air temperature rises above a predetermined value, and to increase this air pressure as the car air temperature falls below the predetermined value.

Inthe position shown in Figure 2, it is assumed that the car air temperature is above the desired value, and accordingly, a low air pressure is applied to the diaphragm I8 and the spring 8| has lifted the plunger 80 and moved the lever 12 to its highest position against a stop 85, placing the governor spring II under maximum. tension. In this condition, the centrifugal elements 84 of the governor are moved inward, turning the shaft in a clockwise direction as viewed in Figure 2 to a point where the throttle valve 56 is opened to a considerable extent, and the, engine E and compressor I8 operate at a comparatively high speed which is limited and controlled by the governor G. The high speed operation of the refrigerating system reduces the car air temperature and when this temperature falls to a predetermined value near the minimum comfortable temperature, the increase in air pressure on the diaphragm 18 moves the plunger 88 and lever 12 to their lowest positions, reducing the tension on the spring II to the minimum value. The centrifugal elements 64 of the governor accordingly move outward, turning the governor shaft 88 in a counterclockwise direction and so closing the throttle valve 55 to a point where the engine and compressor operate at minimum speed. If, under these conditions, the heat load in the car is so light that even at minimum speed operation the refrigeratingsystems lowers the car temperature to the minimum desired value, then the resultant further increase in control air pressure acts through the pneumatic steam valve 55 to cut off the steam supply to the engine E and so stop the refrigerating system. The operating mechanism of the valve 55 is of the pneumatic diaphragm type described above, and air pressure is supplied thereto from the thermostat pipe I through the pipe 88, as shown in Figure 2.

As the car air temperature increases from the minimum value, the reduction in the air pressure controlled by the thermostat 82 first opens the automatic pneumatic steam valve 55 and so starts the engine E and compressor I. at minimum speed. A further rise in car temperature further reduces the control air pressure and the diaphragm I! of the mechanism I8 is lifted by the spring ll, thus lifting the lever I2 and increasing the tension on the governor spring II.

This increased governor spring tension moves the centrifugal elements 84 inward. turning the pressor l0.

Although in the foregoing description, the operation of the control equipment from maximum to minimum speed has been described, it will be understood that under normal conditions, that is, a continuing heat load on the car, the system will operate continuously at some intermediate speed, the governor G maintaining the speed constant at a value determined by the temperature in the car, and the thermostat altering this speed, as required to compensate for changes in car temperature.

From the above description, it will be seen that the governor G and its thermostatic control act tovary the operating speed of the refrigerating system in accordance with changes in the heat load conditions in the car. As long as the car temperature remains constant at the desired value, the governor maintains the compressor speed constant but any change in car temperature produces a corresponding change in compressor speed which counteracts and corrects the car temperature change. With this arrangement, the compressor operates continuously so long as cooling is required, and further operates at all times at the lowest possible speed which will maintain comfortable car conditions under the heat load imposed. Since the compressor efllciency rises as its speed is reduced, the system operates very efliciently and further, since the refrigerating system operates continuously while cooling is required, the losses involved in starting the compressor are avoided. By the use of the system disclosed, dependable cooling can be obtained in all of the cars of long trains. Due to the throttled operation of car cooling units, sudden drops in train line steam pressure are avoidedandthe operation of forward car units does not reduce the steam pressure available on rearward cars to a point where inadequate cooling results. Differences in train steam line pressure are automatically compensated for by the speed governors of the various car units and accordingly it is unnecessary to manually change the adjustment of car equipment in accordance with the position of the car in a train.

I claim: 1. A railway car air conditioning system comprising a car carried refrigerating unit including a mechanical refrigerant compressor, means connected to said refrigerating unit for cooling the interior of a railway car, a variable speed steam engine connected to drive said compressor, means responsive to both the temperature in said car and the speed of said engine for variably controlling the supply of steam to said engine and means responsive to a minimum car temperature for cutting of! the supply of steam to said engine independently of the action of said means responsive to both car temperature and engine speed.

2. A railway car air conditioning system comprising a car carried refrigerating unit including a mechanical refrigerant compressor, means connected to said refrigerating unit for cooling the interior of a railway car, a variable speed steam engine connected to drive said compressor, a speed responsive device driven by said steam engine comprising means moved by centrifugal force acting against a spring, means for variably controlling the rate of supply of steam to said engine in accordance withthe movement of said centrifugally operated means, means responsive to the temperature in said car for varying the force of said spring and further means responsive to the temperature in said car for cutting off the supply of steam to said engine when the car temperature reaches a minimum value.

3. A railway car air conditioning system comprising a car carried refrigerating unit including a mechanical refrigerant compressor, means connected to said refrigerating unit for cooling the interior of a railway car, a variable speed steam engine connected to drive said compressor, a speed responsive device driven by said steam engine comprising means moved by centrifugal force acting against a spring, means for variably controlling the rate of supply of steam to said engine in accordance with the movement of said centrifugally operated means, and means responsive to the temperature insaid car for vary.- ing the force of said spring.

4. In a railway car air-conditioning system, in combination with a steam locomotive and a pinrality of cars connected thereto, a train steam line arranged to be supplied with steam from said locomotive and having a connection extending to each of said cars, a refrigerating unit carried by each car and including a mechanical refrigerant compressor, each refrigerating unit being arranged to cool the interior of the car associated therewith, a variable-speed steam engine on each of said cars for driving the refrigerant compressor thereon, means for supplying steam from said connections to the steam engines on said cars, means on each of said cars responsive to both temperature in such car and the speed of the steam engine thereon for variably controlling the supply of steam from the associated connection to said engine, whereby a sumcient amount of steam is supplied to each engine, independently of the operation of other engines, to operate its associated compressor in accordance with the coolingrequirements of the associated car, and means on each of said cars rcsponsive to a minimum car temperature for cutting off the supply of steam to the engine.

HORACE L. SMITH, JR. 

